Did I ruin my upper receiver?

[MWAG19919]

Why on earth didn’t you just put the fsb (or barrel) in their by itself :/

As far as your question I would guess finish, although 600 seems high

It's a pinned & welded upper, but in hindsight I should have taken the barrel off the upper.

Don’t know about you, but I would spend $70 and not have to worry about it

https://bravocompanyusa.com/bcm-uppe...emo-scratched/

fortunately I purchased one of BCM's demo uppers a while back just in case I ever needed a spare upper, so that'll be today's project. Sucks because I wanted this gun to be mostly Colt, but function is more important.

I work in the coating industry, and anodizing will discolor at high temp, but will not degrade until you get over 1000F. However, I'm not a metallurgist, so it's hard to say whether or not the aluminum was affected. Occasionally we'll see warping of aluminum sheets at temps above 600F, but most of that will depend on the quality of the aluminum. Thicker metal will take longer to warp or soften, and 7075 is probably the best case scenario for holding up at that temp.

How long was it at 600F? That's going to be the determining factor for whether or not your receiver is compromised... I think worst case scenario is that the receiver softened and could have warped out of true "center". Not a risk for catastrophic failure, but it may affect your zero or reduce precision. It could be fine, but you won't know for sure until you shoot it. If you see a major deterioration of accuracy, get a new receiver. If not, just call it a learning experience.

For future reference, I agree with the user above with a strong recommendation to only use coatings that cure at low temps (under 400F) like Duracoat, Alumahyde, Cerakote or even rattle can paint.

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exactly 30 minutes at 600 F

[drewthebrave]

exactly 30 minutes at 600 F

Probably best to just use the BCM upper you have then. I like the BCM receivers, but they take a little extra effort to insert the barrel. To reiterate, I don't think the heat exposure would cause a safety issue, but it could lead to issues with precision from the wakened or softened aluminum.

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[MWAG19919]

Question, though...what happens if you out oil on the upper?

completely cosmetic/aesthetically speaking I’m wondering what oil does as it looks like a match to geissele ddc lol

I put ballistol on it last night and it seemed to even out the finish. It's quite an attractive burnt bronze tbh

Burnt bronze for real on that one.

I was thinking the same. I should sell it on TOS! (jkjk)

You could al least show a pic of the FSB....

You're right, where are my manners?



You'll notice I painted the barrel slightly fore and aft of the fsb. That's because I nicked the bbl with the grinding wheel of the Dremel. It'll be hidden under the handguard so I just wanted to make sure it wouldn't rust.

[RHINOWSO]

Uuuuugh... really?



Bubbas gonna bubba I guess....

[MWAG19919]

To continue with my mishaps, I laid the upper onto a cloth hotpad when I took it out of the oven. Not a problem at the first two curing temps, but at 600 F it melted the hotpad right away. Anyone know how to get the melted cloth off of the metal parts without causing more damage?

[Aetius]

To continue with my mishaps, I laid the upper onto a cloth hotpad when I took it out of the oven. Not a problem at the first two curing temps, but at 600 F it melted the hotpad right away. Anyone know how to get the melted cloth off of the metal parts without causing more damage?

Steel wool

[sva01]

To continue with my mishaps, I laid the upper onto a cloth hotpad when I took it out of the oven. Not a problem at the first two curing temps, but at 600 F it melted the hotpad right away. Anyone know how to get the melted cloth off of the metal parts without causing more damage?

Mag dumps

[Todd.K]

I'm certain you've partially annealed your upper, reducing hardening and strength. It can be heat treated to return it to full strength and worth doing for hands on learning.

It is not unusual for some parts to warp in heat treat. There are several parts in an AR that specify to grind a critical finish dimension after heat treat, like barrel extension lugs.

Aluminum is always machined at finish hardness in my experience. So no idea how much it might warp.

[themonk]

To continue with my mishaps, I laid the upper onto a cloth hotpad when I took it out of the oven. Not a problem at the first two curing temps, but at 600 F it melted the hotpad right away. Anyone know how to get the melted cloth off of the metal parts without causing more damage?

Torch

[markm]

Uuuuugh... really?



Bubbas gonna bubba I guess....

Painful.